Number Eckert

Velocity at the top of the roughness element Cartesian coordinates Eckert number... 

The Eckert number only enters the problem when the viscous dissipation term in the energy equation is significant. For moderate velocities, the viscous dissipation term may be neglected. Under such conditions, the forced convection is characterized by... 

Dimensionless numbers help in convection heat transfer engineering Used to compare relative values in the practice of engineering In convection, there is the Eckert number and the Prandtl number, There is also the Reynolds number, Peclet number and Nusselt number. 

Eckert number Ec vlicP Tw - Tf) Kinetic energy/enthalpy change... 

The first of these is, of course, the Prandtl number which was previously introduced. The second is termed the Eckert number, i.e. ... 

It should be noted that the Eckert number arises from the dissipation term and that it can be written as ... 

For constant fluid property flows, the Eckert number will, for the previously discussed reasons, have a negligible effect and in this case... 

This equation is plotted in Fig. 12-4. It may be noted that the magnetic fiejld will increase the heat-transfer rate for positive values of the Eckert number (7X > T ) and decrease the heat transfer for negative Eckert numbers (T > 7T). This behavior results from the fact that the magnetic field tends to heat the fluid, thereby reducing or increasing the temperature gradient between it and the plate. 

As already mentioned the influence of the Eckert number only has to be considered in exceptional cases. Therefore Ec can normally be left out of (1.46) and (1-47). This will be done throughout what follows. 

E coefficient for turbulent boundary layer, Eq. 6.175 Ec Eckert number, V2/2i... 

Rearranging Eq. 22 and using the following definition of the Eckert number. 

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